Ultrasonic wound treatment apparatus and associated method

ABSTRACT

An ultrasonic medical treatment probe has a head with a distal-most circular rim extending along an endless uninterrupted perimeter around a broad recess and formed with a series of serrations or teeth. The rim is thin in comparison to the width of the recess. The serrations or teeth preferably extend continuously along an entire circumference or length of the rim. The probe head is provided along the rim with a plurality of notches or openings communicating with the recess.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/797,660 filed Jul. 13, 2015, now U.S. Pat. No. 9,872,697.

BACKGROUND OF THE INVENTION

This invention relates to ultrasonic surgical instruments and associatedmethods of use. More particularly, this invention relates to thetreatment of wounds with ultrasound energy. The treatment contemplatedby this invention includes fragmentation and emulsification of hard andsoft tissue in a clinical environment while reducing unwanted heat andcollateral tissue damage.

Over the past 30 years, several ultrasonic tools have been inventedwhich can be used to ablate or cut tissue in surgery. Such devices aredisclosed by Wuchinich et al. in U.S. Pat. No. 4,223,676 and Idemoto etal in U.S. Pat. No. 5,188,102.

In practice, these surgical devices include a blunt tip hollow probethat vibrates at frequencies between 20 kc and 100 kc, with amplitudesup to 300 microns or more. Such devices ablate tissue by eitherproducing cavitation bubbles which implode and disrupt cells, bygenerating tissue compression and relaxation stresses (sometimes calledthe jackhammer effect) or by other mechanisms such as micro streaming ofbubbles in the tissue matrix. The effect is that the tissue becomesliquefied and separated. The fragmented tissue becomes emulsified withan irrigant solution. The resulting emulsion or slurry of tissue debrisis then aspirated from the site. Bulk excision of tissue is possible byapplying the energy around and under an unwanted tissue mass to separateit from the surrounding structure. The surgeon can then lift theseparated tissue mass out using common tools such as forceps.

The tubular probe is excited by a transducer of either the piezoelectricor magnetostrictive type that transforms an alternating electricalsignal within the frequencies indicated above into a longitudinal ortransverse vibration. When the probe is attached to the transducer, thetwo become a single element with series and parallel resonances. Thedesigner will try to tailor the mechanical and electricalcharacteristics of these elements to provide the proper frequency ofoperation. Most of the time, the elements will have a long axis that isstraight and has the tip truncated in a plane perpendicular to the longaxis. This is done for simplicity and economic considerations. In almostall applications, whether medical or industrial, such an embodiment ispractical and useful. However, in applications such as the debridementof burns, wounds, diabetic ulcers or ulcers induced by radiationtreatments, the blunt straight probe has been shown to be less effectivein removing the hard eschar buildup that occurs when the wound ishealing. This eschar buildup must be removed so that the healthy tissueis exposed and allowed to close the wound to provide complete healingwith minimal scar tissue formation. Also, the small diameter tip, sinceit is cannulated, has a small annular area with limits energytransmission into the wound. This extends the length of the procedureand causes operator fatigue and patient discomfort.

Therefore, it was desired to provide a probe that can be mated to anultrasonic surgical aspirator that increases the efficiency ofemulsification, does not heat up the operative site and lowers the timeof operation.

In response to this need, a series of devices were developed which havebeen proven to address at least some of the shortcomings of the previoustechniques. These devices are described in U.S. Pat. No. 7,931,611issued Apr. 26, 2011. The devices have been shown to be effective inclinical use for the removal of necrotic tissue and some softer types ofeschar.

High temperature burns produce a tough, leathery type of eschar. Whilethe eschar can slough off naturally, its removal through surgicaldebridement is often necessary in order to prevent infection. This iseven more important for immuno-compromised patients. A frequently usedeschar removal option involves the use of a manual dermatome such as aWeck knife. The surgeon cuts thin slices of eschar until the healthytissue is exposed. Bleeding is the key visual indicator when the Weckknife has reached healthy tissue. Ideally, the eschar should be removedwithout any insult to the healthy tissue below. As this is not possible,the thinner the layer of healthy tissue removed during debridement, themore successful the eschar removal procedure.

The ultrasonic debridement of wounds, as described above, has alreadybeen proven as an extremely precise, necrotic tissue removal method withthe added benefit of minimum impact to the healthy tissue. Ultrasoundwound debridement probes are used for debriding complex tissuetopographies with minimal loss of healthy tissue. This is not possibleto duplicate with sharps, such as scalpels or Weck knives.

Because some of the mechanical properties of the hightemperature-induced eschar, such as elasticity, are close to those ofhealthy tissue, ultrasonic debridement using the ultrasonic debridementtools developed to date is problematic.

OBJECTS OF THE INVENTION

An object of the present invention is to provide an improved ultrasonicsurgical instrument for use in wound treatment.

A more particular object of the present invention is to provide such aninstrument that will improve wound healing times.

Another particular object of the present invention is to provide such aninstrument that may be used in the debridement of wounds that evince atough, leathery type of eschar.

It is a further object of the present invention to provide such animproved ultrasonic surgical instrument that is easy to use.

It is an associated object of the present invention to provide animproved method of debridement of wounds, such as high temperature burnsexhibiting a tough, leathery type of eschar.

These and other objects of the invention will be apparent from thedrawings and descriptions herein. Although every object of the inventionis attained in at least one embodiment of the invention, there is notnecessarily any embodiment which attains all of the objects of theinvention.

SUMMARY OF THE INVENTION

An ultrasonic medical treatment probe in accordance with the presentinvention comprises a shaft or shank, a connector and a probe head. Theconnector, disposed at one end of the shaft or shank, is configured forcoupling to a source of ultrasonic vibratory energy. The probe head islocated at an end of the shaft or shank opposite the connector andincludes a recess opening onto a distal end plane of the instrument. Theprobe head has a distal-most rim extending along an endlessuninterrupted perimeter around the recess and is formed with a series ofserrations or teeth.

Pursuant to the present invention, the distal-most rim is disposed in aplane, exemplarily, but not necessarily, oriented at a 90° anglerelative to an axis of the shaft.

Preferably, the rim is circular, the probe head has a cup-shapedconfiguration, and the rim constitutes an edge of the probe head. As inany typical cup shape, the rim is thin in comparison to the width of therecess. While the rim is no thicker than a few millimeters, the recessis typically 5-15 millimeters in diameter. Thus, the diameter of therecess is roughly an order of magnitude larger than the width of therim.

The serrations or teeth preferably extend continuously along an entirecircumference of the rim. The resulting symmetry facilitates use of thedevice to debride a wound surface. The entire geometry of the probe headis particularly conducive to effective removal of eschar from tissuesurfaces having high-temperature burns.

Pursuant to another feature of the present invention, the probe head isprovided along the rim with a plurality of notches or openingscommunicating with the recess. Preferably, the probe head is providedalong the rim with exactly four notches or openings communicating withthe recess.

A wound debridement method in accordance with the present inventionutilizes an ultrasonic probe having a shaft or shank, a connector at oneend of the shaft or shaft configured for coupling to a source ofultrasonic vibratory energy, and a probe head at an end of the shaft orshank opposite the connector, the probe head including a recess openingonto a distal end plane, the probe head having a distal-most rimextending along an endless uninterrupted perimeter around the recess,the rim being formed with a series of serrations or teeth. The methodcomprises placing the rim including the serrations or teeth in contactwith a target surface of a patient, moving the probe so that the rimmoves in a predetermined pattern parallel to and along the targetsurface while the rim including the serrations or teeth is in contactwith the surface, and, during the moving of the probe, generating anultrasonic standing wave in the probe to vibrate the rim and therebydebride the target surface. Preferably, liquid is conducted through achannel or bore in the probe shaft to the recess in the probe headduring the moving of the probe in contact with the target surface.

The predetermined pattern of probe motion may be a series of parallelpasses adjacent to and preferably overlapping slightly to ensure removalof a continuous layer of eschar at a burn site. The same result may beachieved by moving the probe in a series of overlapping loops. The loopsmay be roughly circular and the overlapping circles may be disposed in alinear arrangement to generate a rectangular swath of debrided tissuesurface. Again, several passes of looping probe movements may beundertaken to debride a wide area. In general, the moving of the probeis such that the serrated rim is moved laterally within a planeconstituting at least a portion of the target surface.

It is contemplated that the serrated rim of the probe head is vibratedat velocities of 10 to 18 m/s RMS. A combination of frequency-amplitudeoperational parameters may be selected to ensure such velocities. Forexample, for 22.5 KHz the output amplitude range that produces thedesired speed interval of 10-18 m/s RMS is 200-360 um.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view, partially schematized, of anultrasonic wound debridement probe in accordance with the presentinvention, showing a serrated distal edge.

FIG. 2 is a partial longitudinal cross-sectional view taken along lineII-II in FIG. 1.

FIG. 3 is a perspective view of the probe of FIGS. 1 and 2.

FIG. 4 is a partial side elevational view, on an enlarged scale, of thedistal edge of the probe of FIGS. 1-3.

FIG. 5 is a diagram showing a pattern of use of the probe of FIGS. 1-4.

FIG. 6 is a diagram showing an alternative pattern of use of the probeof FIGS. 1-4.

DETAILED DESCRIPTION

As illustrated in FIGS. 1-3, an ultrasonic medical treatment probe 10comprises a shaft or shank 12, a connector 14, and a probe head 16.Connector 14, disposed at one end of shaft or shank 12, is configuredfor coupling to a source of ultrasonic vibratory energy. Probe head 16is located at an end of shaft or shank 12 opposite the connector 14 andis transversely enlarged so as to define a large recess 18 opening ontoa distal end plane 20 of the instrument. Probe head 16 has a distal-mostrim 22 extending along an endless uninterrupted perimeter around recess18 and is formed with a series of serrations or teeth 24 pointed ortapering in a distal direction.

Distal-most rim 22 is disposed in plane 20 that is, exemplarily, but notnecessarily, oriented at a 90° angle relative to an axis of shaft 12.

Preferably, rim 12 is circular, probe head 16 has a cup-shapedconfiguration, and rim 22 constitutes an edge of the probe head. As inany typical cup shape, rim 22 is thin in comparison to the width ofrecess 18. While the rim 22 is no thicker than a few millimeters, therecess is typically at least 5-15 millimeters in diameter. Thus, thediameter of recess 18 is roughly an order of magnitude larger than thewidth of rim 22.

Serrations or teeth 24 preferably extend continuously along an entirecircumference of rim 22. The resulting symmetry facilitates use of thedevice 10 to debride a wound surface. The entire geometry of probe head16 is particularly conducive to effective removal of eschar from tissuesurfaces having high-temperature burns.

Probe head 16 is preferably provided along rim 22 with a plurality ofmutually spaced notches or openings 26 communicating with recess 18. Asillustrated, probe head 16 is provided along rim 22 with exactly fournotches or openings 26 communicating with recess 18. Notches or openings26 are substantially larger than serrations or teeth 24. Serrations orteeth 24 extend continuously along rim or edge 22 between notches oropenings 26. Serrations or teeth 24 are spaced from one another by gaps(not separately enumerated) substantially smaller than notches oropenings 26.

Shaft or shank 12 is formed with a central channel or bore 28 thatcommunicates at a distal end with recess 18 and penetrates at a proximalend through connector 14 for communicating via a handpiece (not shown)with a pressurized source of irrigation liquid. The irrigation liquid istypically a saline solution that may have antibiotic and/or anestheticconstituents.

A wound debridement method utilizing probe 10 entails manipulating theprobe to place rim 22 including serrations or teeth 24 in contact with atarget surface of a patient, and moving the probe so that the rim movesin a predetermined pattern parallel to and along the target tissuesurface while the rim including the serrations or teeth is in contactwith the tissue surface. During the moving of probe 10, one generates anultrasonic standing wave in the probe to vibrate rim 22 and theserrations or teeth 24 thereof, thereby debriding the target surface.Irrigation liquid is conducted through channel or bore 28 in probe shaft12 to recess 18 in probe head 16 and out through notches 26 (asindicated by arrows 40) during the moving of the probe 10 in contactwith the target surface.

One pattern of probe motion, depicted in FIG. 5, is a series of parallelpasses 30 adjacent to each other and preferably overlapping slightly tothereby ensure removal of a continuous or uninterrupted layer of escharat a burn site. The parallel passes 30 may be separate, that is,temporally spaced owing to a lifting of the probe 10 away from thetarget skin surface and a repositioning of the probe prior to motion inthe same direction as indicated by arrows 32. Alternatively, alternatepasses 30 may be in an opposite direction, with the probe remaining onthe target skin surface during the changes in direction of probe motion.

Another pattern of probe motion, shown in FIG. 6, is a series ofoverlapping loops 34. The loops 34 are roughly circular and theoverlapping circles may be distributed in arrays 36 to generate linearpasses each clearing a rectangular swath or path of debrided tissuesurface. Again, several debridement passes 36 of looping probe movementmay be undertaken to debride a wide area. The parallel passes 36 may beseparate, that is, temporally spaced owing to a lifting of the probe 10away from the target skin surface and a repositioning of the probe priorto motion in the same direction as indicated by arrows 38.Alternatively, alternate looping passes 36 may be in an oppositedirection, with the probe remaining on the target skin surface duringthe changes in direction of probe motion.

In general, the moving of probe 10 is such that the serrated rim ismoved laterally within a plane constituting at least a portion of thetarget surface.

It is contemplated that the serrated rim of the probe head is vibratedat velocities of 10 to 18 m/s RMS. A combination of frequency-amplitudeoperational parameters may be selected to ensure such velocities. Forexample, for 22.5 KHz the output amplitude range that produces thedesired speed interval of 10-18 m/s RMS is 200-360 um.

Probe 10 and the use thereof in wound debridement combines the followingparameters at the probe-tissue interface: (1) high contact pressure, (2)high velocities of rim 22 and teeth 24, and (3) irrigation via channel28 and recess 18. Probe 10 has proven highly efficient in the preciseand efficient removal of tough, leathery type of eschar produced by hightemperature burns. Key elements of probe 10 include an annular contactarea fitted with serrated edge 22 to ensure a high contact pressure,needed for tissue penetration and disruption, at the probe-tissueinterface. Notches 26, set 90° apart around the annular perimeter of thedistal end of the instrument head 16, allow irrigant to exit the probeeven during full contact with the target tissue.

Again, an optimal operation of probe 10 contemplates a combination offrequency-amplitude operational parameters that ensure high velocitiesexemplarily between 10 and 18 m/s RMS. Example: for 22.5 KHz the outputamplitude range that produces the desired speed interval of 10-18 m/sRMS is 200-360 urn.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. In some applications it may be beneficial if rim 22has a shape other than circular, for instance, oval or elliptical oroblong with rounded or truncated corners. Accordingly, it is to beunderstood that the drawings and descriptions herein are proffered byway of example to facilitate comprehension of the invention and shouldnot be construed to limit the scope thereof.

1. An ultrasonic medical treatment probe comprising: a shaft or shank; asource of ultrasonic vibratory energy; a connector at one end of saidshaft or shaft operatively coupling same to said source of ultrasonicvibratory energy; and a probe head at an end of said shaft or shankopposite said connector, said probe head including a recess opening ontoa distal end plane, said probe head having a distal-most rim or edgeextending around said recess, said distal-most rim or edge being formedwith a series of serrations or teeth, said distal-most rim or edge beingfurther formed with a plurality of notches or openings communicatingwith said recess, said notches or openings being substantially largerthan said serrations or teeth, said serrations or teeth extendingcontinuously along said distal-most rim or edge between said notches oropenings, said serrations or teeth being spaced from one another by gapssubstantially smaller than said notches or openings.
 2. The probedefined in claim 1 wherein said distal-most rim or edge is disposed in aplane.
 3. The probe defined in claim 2 wherein said distal-most rim oredge is circular.
 4. The probe defined in claim 3 wherein said probehead has a cup-shaped configuration.
 5. (canceled)
 6. The probe definedin claim 1 wherein said plane is oriented perpendicularly to an axis ofsaid shaft or shank.
 7. The probe defined in claim 1 wherein said probehead has a cup-shaped configuration.
 8. The probe defined in claim 1wherein said distal-most rim or edge is circular.
 9. (canceled) 10.(canceled)
 11. The probe defined in claim 1 wherein said probe head isprovided along said distal-most rim or edge with exactly four saidnotches or openings communicating with said recess.
 12. A wounddebridement method comprising: providing an ultrasonic probe having ashaft or shank, a connector at one end of said shaft or shaft configuredfor coupling to a source of ultrasonic vibratory energy, and a probehead at an end of said shaft or shank opposite said connector, saidprobe head including a recess opening onto a distal end plane, saidprobe head having a distal-most rim or edge extending around saidrecess, said distal-most rim or edge being formed with a series ofserrations or teeth, said distal-most rim or edge being further formedwith a plurality of notches or openings communicating with said recess,said notches or openings being substantially larger than said serrationsor teeth, said serrations or teeth extending continuously along saiddistal-most rim or edge between said notches or openings, saidserrations or teeth being spaced from one another by gaps substantiallysmaller than said notches or openings; coupling said connector to asource of ultrasonic vibratory energy; placing said distal-most rim oredge including said serrations or teeth in contact with a target surfaceof a patient; moving said probe so that said distal-most rim or edgemoves in a predetermined pattern parallel to and along said targetsurface while said distal-most rim or edge including said serrations orteeth is in contact with said target surface; and during the moving ofsaid probe, generating an ultrasonic standing wave in said probe tovibrate said distal-most rim or edge and thereby debride said targetsurface.
 13. The method defined in claim 12 wherein during the moving ofsaid probe, said distal-most rim or edge is moved laterally within aplane constituting at least a portion of said target surface.
 14. Themethod defined in claim 12 wherein said plane is orientedperpendicularly to an axis of said shaft or shank.
 15. The methoddefined in claim 12 wherein said distal-most rim or edge is vibrated atvelocities of 10 to 18 m/s RMS.
 16. The probe defined in claim 1 whereinsaid serrations or teeth project in a distal direction from saiddistal-most rim or edge and are disposed only on a side of saiddistal-most rim or edge facing in said distal direction.
 17. The probedefined in claim 1 wherein said notches or openings extend a firstdistance along said distal-most rim or edge, said serrations or teetheach extending a second distance along said distal-most rim or edge,said first distance being more than two times said second distance. 18.The probe defined in claim 1 wherein said distal-most rim or edge iscircular and a multiplicity of said serrations or teeth are disposedbetween consecutive or successive ones of said notches or openings alongsaid distal-most rim or edge.
 19. An ultrasonic medical treatment probecomprising: a shaft or shank having a longitudinal axis; a connector atone end of said shaft or shaft configured for coupling to a source ofultrasonic vibratory energy; and a probe head at an end of said shaft orshank opposite said connector, said probe head including a recessopening onto a distal end plane oriented perpendicularly to saidlongitudinal axis, said probe head having a distal-most rim or edgeextending around said recess and in said distal end plane, saiddistal-most rim or edge being formed with a series of serrations orteeth that point or taper in a distal direction from said distal endplane.
 20. The probe defined in claim 19 wherein said distal-most rim oredge is further formed with a plurality of notches or openingscommunicating with said recess, said notches or openings beingsubstantially larger than said serrations or teeth, a plurality of saidserrations or teeth extending along said distal-most rim or edge betweenconsecutive or successive ones of said notches or openings.
 21. Theprobe defined in claim 20 wherein said distal-most rim or edge iscircular.
 22. The probe defined in claim 19 wherein said distal endplane is oriented perpendicularly to an axis of said shaft or shank.